Ignition distributor



`une 6, 1939. R; H. G|B5ON 2,161,251

IGNITION DISTRIBUTOR INVENTOR. /'f /17' ff. 6/1560/1/ BY Q,... @ad

ATTORNEY,

June 6, 1939. R. H. GIBSON 2,161,251

IGNITION DISTRIBUTOR Filed Nov. 6, 1937 2 Sheets-Sheet 2 INVENTOR.675601/ ATTORNEY.

Patented June 6, 1939 UNITED STATES PATENT OFFICE American BoschCorporation,

Springfield,

Mass., acorporation of New York Application November 6, 1937, Serial No.173,073

1 Claim.

This invention relates to ignition distributors of the sliding contactor brush type for magnetos or the timer distributors of battery ignitionsystems.

In brush types of distributors it is desirable to use carbon brusheswhich bear upon a rotating plate. If the carbon is soft the platenecessarily becomes smeared with an annular ring of carbon which forms aconducting path that results in a 1Q short circuit or electricalconnection between brushes and thus brings about misring at the sparkplugs in some or most of the engine cylinders. If, on the other hand,the brush composition is made hard in order to reduce this carbon 1 5smearing then the track is scored or cut which results in undue wear ofthe parts.

It is a primary object of the present invention to obviate the abovementioned difliculties and permit the use of softer carbon brushes thanwould otherwise be the case, thereby preventing the high rate of cuttingof the track upon the rotating disc and at the same time preventing thesmear of conducting carbon from accumulating on the surface of the plateto a sufficient extent to short circuit or connect the brushes of thedistributor. To this end I provide a means forming a non-cutting scraperto partially or entirely remove the carbon as it is smeared upon thetrack by the carbon brushes of the distributor connected to the sparkplugs. This non-cutting scraper may be in the form of a brush ofinsulating material placed in a position to Contact the rotating discand wipe the track where the smear is normally formed. This cleaningoperation may also be effected by making alternate brushes of somematerial other than carbon, such as stainless steel, which forms a goodconducting and carbon scraping brush but which does not cut or smear therotating disc.

In both of the foregoing arrangements the carbon brushes of thedistributor connected to the spark plugs can be of softer carbon thanwould otherwise be the case because even if the brush is so soft that itwould ultimately smear the track upon the rotating disc it does no harmin the distributor because the smear is continuously removed andprevented from forming a short circuiting or electrically connectingpath on the track. Also the carbon brushes may be of lower grade andtherefore less expensive than was formerly the case, and require littleor no inspection in assembly for their tendency to smear. Furthermore,the tension of the springs behind 55 the brushes is not so critical, andthe metal insert or inserts in the rotating disc of the distributor donot require as smooth a finish as formerly.

The above and other objects and features of the invention will beapparent to` those skilled in the art from a consideration of thefollowing detailed 5 description taken in conjunction with theaccompanying drawings, in which:

Fig. lis a section through an electrical distributor constructed inaccordance with the invention; Fig. 2 is an inner face view of thedistributor 10 plate; Fig. 3 is a plan view of the rotating distributormember thereof; and Fig. 4 is a view similar to Fig. 2 of a modifiedform of the invention.

Referring to the drawings reference numeral I 15 indicates a distributorcap or plate having a high tension lead 2 embedded therein and which, inthe form shown, is adapted to be connected to the high tension terminalof a stationary ignition coil of a magneto by Way of a terminal plug 3in the 20 upper portion of the distributor cap. The opposite end of thelead 2 is connected to a terminal plug 4, toward the central portion ofthe cap, in which plug is mounted a brush 5 pressed by a spring 6 intocontinuous electrical contact with a rotor I mounted on a shaft 8adjacent the inner edge of the distributor cap I. The rotor I is formedof hard insulating material and, as may be seen in Fig, 3, carries ametallic conducting member 9 embedded therein flush with the surfacethereof. This member has a portion I0 positioned toward the center ofthe rotor 'I forming a central distribution point for the distributorand being adapted for continuous contact with the brush 5, and it alsohas an outwardly extending portion II. The distributor cap also carriesa number of terminal plugsA I2 each of which is adapted for connectionto a suitable spark plug lead 20 and each of which contains a brush I3pressed toward the rotor 1 by a spring I4. The 40 brushes I3 are thusadapted to contact the outwardly extending portion II of the conductingmember 9 once during each revolution of the rotor I thus completing theelectrical circuit of the spark plugs associated with the particularterminals I2 in a manner Well lmown in the art.

In constructions of the type just described, obviously the brush I3 mustbe of good conducting material and yet must not be of such a hardcomposition that it will tend to cut a circular groove in the rotor 1.For this reason such brushes have commonly been formed of soft carbon.However, such soft carbon tends to mark or smear the face of the rotor 1with a continuous line of lne carbon deposit which during the course ofuse becomes of sufficient depth and consistency to form an electricallyconducting path between the outwardly extending portion II of theconducting member 9 and one or more of the brushes I3. Thus as a brushI3 passes over the conducting portion I I onto the insulating portion ofthe rotor the circuit is not interrupted but continues from theconducting member through the carbon smear to the brush and thusinterferes with the proper ignition in the cylinders of the engine. Onthe other hand, if soft carbon is not used for the brushes I3 theinsulating portion of the rotor 'I becomes scored or cut and since thematerial of the rotor and the conducting member are of differenthardness the scored path is uneven causing one portion thereof toproject above another and such projecting portions tend to sheaf oif thetip of the hard brush causing it to wear even more rapidly than if itwere soft.

To obviate such difliculties I provide a member for removing the carbonsmear substantially as rapidly as it is formed so that the brushes I3may be of comparatively soft carbon and yet there Will be o conductingsmear formed on the face of the rotor. In the form shown in Figs. 1 and2 this member consists of a brush I5 which is preferably of insulatingmaterial, such as bakelized linen, and which is pressed by a spring I5against the face of the rotor 'I to continuously Wipe the path free fromsoft carbon deposit. In this form the wiping brush I5 is separate fromthe electrical system being disposed in the case of a multicylinderengine between two of the electrical conducting brushes I3.

In the form shown in Fig. 4 a similar result is achieved by utilizingone or more of the brushes of the distributor as the wiping member ormembers. In this form some of the terminal plugs I'I are provided withsoft carbon brushes I8. One

or more of the brushes, and preferably alternate brushes I9, are formedof metal, such as stainless steel. In such a construction the metalbrush I9 tends to Wipe off the carbon deposited by the preceding carbonbrush I8. The soft carbon on the track or gathered by the metal brushtends to lessen the friction thereof upon the track thus preventing thismetallic member from cutting or scoring the face of the rotor while atthe same time preventing carbon deposit from accumulating upon thesurface of the rotor sufficient to form a conducting path thereon.

While I have here described but two embodiments of the invention, otherembodiments within the scope of the appended claim will be obvious tothose skilled in the art. In the forms Y shown the distributors are of anumber of types suitable for use in conjunction with magnetos, but theapplication of the invention to other forms of distributors and to othertypes of electrical ignition systems, such as the battery ignition type,Will be obvious from the applications shown.

What is claimed is:

In an electrical distributor, a rotating member of insulating materialhaving a conducting member extending from a central distribution pointto a distribution path in registry with a spark plug lead, an'electrical connection continuously in contact with said rotating member,a carbon brush associated with said spark plug lead in continuousengagement with said rotating member for making intermittent electricalcontact with said conducting member, and means comprising a stationarynon-cutting scraper of insulating material spring-pressed intocontinuous engagement with the rotatable member and positioned to removethe carbon as it is smeared thereon by the carbon brush.

ROBERT H. GIBSON.

